Plastic containers such as bottles for liquid beverages are manufactured and filled according to different methods including blow molding or stretch-blow molding.
According to known methods a plastic preform is first manufactured through a molding process and then heated before being positioned inside a blowing mold.
The preform usually takes the form of a cylindrical tube closed at its bottom end and open at its opposite end.
Once the preform has been positioned within the mold only the open end of the preform is visible from above the mold.
The methods make use of a stretch rod, which is downwardly engaged into the open end of the preform so as to abut against the closed bottom end thereof. The stretch rod is further actuated to be urged against the closed end, thereby resulting in stretching down the preform.
According to one known method, after the stretching phase has been initiated, the preform is blown with pressurized air in order to form the container, and after a cooling period, the container can be filled with a liquid product.
When the beverage is a carbonated liquid, it is necessary to reduce the foaming tendency of the product, but also to keep the carbonation properties of the carbonated liquid beverage once filled in the container. A known solution is to cool the carbonated product to a temperature between 10 to 17° C. before filling it in the container. This cooling step increases the manufacturing time and causes high energy consumption, especially in areas with high temperature climate conditions.
According to another manufacturing method, after the stretching phase has been initiated, a liquid is injected into the preform through its open end. This is disclosed, for instance, in Applicant's own patent EP 1 529 620 B1. This liquid injection causes expansion of the preform until coming into contact with the inner walls of the mold, thereby achieving the final shape of the container. The injected liquid is preferably the liquid the container is to be filled with. In case of a carbonated product, the foaming tendency of these products during filling of the container has to be managed.
With the above method, cooling of the carbonated liquid product is not a solution because of the impact of the temperature of the cooled carbonated liquid on the expansion of the preform and because of important energy consumptions.
There is, therefore, a need for a method and a system enabling simultaneous forming and filling of a container with a carbonated liquid, while avoiding foaming of the carbonated liquid and keeping the required carbonation properties of the carbonated liquid.